Printed circuit board and method for manufacturing the same

ABSTRACT

Disclosed herein are a printed circuit board and a method for manufacturing the same. The printed circuit board includes: a base substrate having a metal pattern for a circuit; and a surface roughness provided on the metal pattern, wherein the surface roughness has a first surface roughness in an anchor structure and a second surface roughness having a black oxide layer in a needle structure formed on the first surface roughness.

CROSS REFERENCE TO RELATED APPLICATION

This application is a Divisional application of U.S. application Ser.No. 13/308,439, filed Nov. 30, 2011, which claims the benefit under 35U.S.C. §119(a) of Korean Patent Application No. 10-2010-0138241, filedDec. 29, 2010, in the Korean Intellectual Property Office, thedisclosures of both of which are incorporated herein by reference forall purposes.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a printed circuit board and a methodfor manufacturing the same.

2. Description of the Related Art

Technical development for size and weight reduction, and thinner andsimpler configuration of an electronic apparatus such as a laptopcomputer, a net-book, a tablet PC, a smart phone, a navigator, and thelike has remarkably increased. Technologies for size and weightreduction, and thinner and simpler configuration of an electronicapparatus require not only techniques of decreasing the size ofelectronic components mounted on the electronic apparatus andmicro-processing the same but also design techniques for optimizing amounting space. Especially, a printed circuit board enabling highdensity and high integration mounting of electronic components thereonis essentially demanded.

Single-sided printed circuit boards, double-sided printed boards andmultilayer printed circuit boards are currently manufactured andavailable on the market.

The multilayer printed circuit board is configured by laminating aplurality of single-sided boards wherein a specific conductive materialis embedded in an internal layer to increase a mounting density ofelectronic components while improving variation in electricalcharacteristics, thus being preferably employed.

For production of a multilayer printed circuit board (‘PCB’), in orderto protect internal circuits against surrounding conditions and maximizeinterlayer adhesion during lamination to combine respective internal andexternal layers, thus securing the reliability of the PCB, a variety ofsurface treatment processes have been conducted.

FIG. 1 is a schematic view illustrating a surface of an internal circuitsurface-treated by a conventional brown oxide treatment method throughacid type etching.

Referring to FIG. 1A, a PCB 10 has copper (Cu) patterns 12 as aninternal circuit formed on both sides of an insulating layer 11. Whenthe Cu patterns 12 are surface treated by brown oxide treatment, ananchor type surface roughness 12 a and an organic layer 13 are formed ona surface of the Cu patterns 12, as shown in FIG. 1B.

FIG. 2 is a schematic view illustrating a surface of an internal circuitsurface-treated by a conventional alkali reduction type black oxidetreatment process.

Referring to FIG. 2A, a PCB 20 has Cu patterns 22 as an internal circuitformed on both sides of an insulating layer 21. When the Cu patterns 22are surface treated by black oxide treatment using an oxidizing agentand an alkali material, a black oxide layer 23 in a needle structurecontaining Cu(II) oxide and Cu(I) oxide is formed on a surface of thesurface-treated Cu patterns 22 a, as shown in FIG. 2B. Moreover, asshown in FIG. 2C, a post-dipping process using a reducing agent and analkali material is carried out to enable reduction of a surface of theblack oxide layer 23 while maintaining the needle structure thereof,thereby forming a Cu reduction layer 24.

FIG. 3 is a schematic view illustrating a surface of an internal circuitsurface-treated by a conventional black oxide treatment method throughacid dissolution.

Referring to FIG. 3A, a PCB 30 has Cu patterns 32 as an internal circuitformed on both sides of an insulating layer 31. When the Cu patterns 32are surface treated by a black oxide treatment method, a black oxidelayer 33 in a needle structure containing Cu(II) oxide and Cu(I) oxideis formed on a surface of the surface-treated Cu patterns 32 a, as shownin FIG. 3B. Moreover, as shown in FIG. 3C, a post-dipping process usingan acidic dissolving agent is carried out to form a Cu(I) oxide layer 34wherein a needle structure is converted into a micro-granular structure.

For products manufactured by the foregoing surface treatment processes,an epoxy based interlayer bonding resin (often referred to as ‘prepreg’)having a low glass transition temperature Tg (less than 140° C.) and ahigh resin impregnation rate has generally been used.

However, with the rapidly growing technologies in electronics asdescribed above, a high reliability material used for manufacturing anelectronic product with high density, high integration, ultrathin filmand high economical efficiency is also required.

As for lamination of products treated by a conventional brown oxidetreatment or black oxide treatment method, a variety of prepregs havingspecific characteristics such as a normal Tg (less than about 140° C.),a middle Tg (about 150 to 170° C.), a high Tg (more than about 180° C.),a low dielectric constant (Dk; less than about 4.2), a low dielectricloss (Df; less than about 0.015) and/or halogen-free properties(including antimony-free or red phosphorous-free properties) aregenerally used. For instance, when a bismaleidotriazine (BT) resinhaving a Tg of more than 200° C., excellent characteristics such as heatresistance, dielectric properties, insulating properties and/ormigration-resistance, and favorable activity under molding conditions isused as a prepreg for manufacturing a semiconductor packaging substrate,the substrate treated by a conventional brown oxide treatment or blackoxide treatment method has a peel strength of about 0.2 kgf/cm, which isnot suitable for a high reliability product requiring a peel strength ofat least 0.4 kgf/cm.

In particular, if a black-oxide treatment process is conducted in ahorizontal roll type line, a substrate may have numerous roll marksgenerated on a surface thereof, which in turn causes Cu exposure, thuscausing problems in interlayer adhesion and appearance of a finalproduct.

SUMMARY OF THE INVENTION

The present invention has been made in an effort to provide a surfacetreatment process for manufacturing a general multilayer printed circuitboard (PCB′).

Further, the present invention has been made in an effort to provide amethod for surface treatment of a circuit to improve interlayer adhesionof a PCB, which includes using a variety of prepregs having a normal Tg,a middle Tg, a high Tg, a low Dk, a low Df and/or excellent halogen-freeproperties, especially, a BT resin with excellent heat resistance,dielectric properties, insulating properties and migration-resistance,as well as PCBs manufactured by the same.

Further, the present invention has been made in an effort to provide aPCB having minimum roll marks generated during a horizontal rollprocess, by decreasing a thickness of a black oxide layer, as comparedto a conventional black oxide treatment method, as well as a method formanufacturing the same.

According to a preferred embodiment of the present invention, there isprovided a printed circuit board (PCB) including: a base substratehaving a metal pattern for a circuit; and a surface roughness formed onthe metal pattern, wherein the surface roughness has a first surfaceroughness in an anchor structure and a second surface roughness having ablack oxide layer in a needle structure formed on the first surfaceroughness.

The second surface roughness of the PCB may further include a reductionlayer formed by reducing a surface of the black oxide layer.

Preferably, the black oxide layer in a needle structure may have athickness in the range of 0.05 to 1.0 mg/cm².

A metal of the metal pattern of a PCB may comprise Cu or a Cu alloy.

According to another preferred embodiment of the present invention,there is provided a printed circuit board (PCB) including: a basesubstrate having a metal pattern for a circuit; and a surface roughnessformed on the metal pattern, wherein the surface roughness includes afirst surface roughness in an anchor structure and a second surfaceroughness having a black oxide layer in a granular structure formed onthe first surface roughness.

Preferably, the black oxide layer in a granular structure may have athickness in the range of 0.005 to 0.4 mg/cm².

According to another preferred embodiment of the present invention,there is provided a method for manufacturing a printed circuit board(PCB), including: treating a metal surface for a circuit with an etchingsolution for forming an anchor structure, to form a first surfaceroughness in an anchor structure on the metal surface; pre-dipping themetal surface having the first surface roughness to activate the same;and subjecting the activated metal surface into a black-oxide treatmentto form a second surface roughness having a black oxide layer in aneedle structure on the first surface roughness having an anchorstructure.

The method may further include degreasing the metal surface for acircuit, before the formation of the first surface roughness.

According to a preferred embodiment of the present invention, the methodmay further include post-dipping the black-oxide treated metal surfaceusing a basic reducing agent to form a reduction layer, after theformation of the second surface roughness.

According to a preferred embodiment of the present invention, the methodmay further include post-dipping the black-oxide treated metal surfaceusing an acidic dissolving agent to convert the needle structure of theblack oxide layer into a granular structure, after the formation of thesecond surface roughness.

The etching solution may contain an etchant for forming an anchorstructure, which includes an inorganic acid, an organic acid, anoxidizing agent, and an azole compound. Here, a content of the etchantfor forming an anchor structure may range from 0.5 to 30 wt. % of theetching solution.

The pre-dipping may be performed using a pre-dipping solutioncontaining, preferably, an organic acid, an inorganic acid, a baseand/or an oxidizing agent, alone or in combination of two or morethereof.

The black-oxide treatment may be conducted using a black-oxide treatingreaction solution containing, preferably, an oxidizing agent and a base.

The basic reducing agent may be selected from a group consisting ofdimethylamine borane (DMAB), morpholine borane (MPB), formalin (HCHO),sodium borohydride (NaBH₄), potassium borohydride (KBH₄) and mixturesthereof.

The acidic dissolving agent may be selected from a group consisting ofan inorganic acid, an organic acid, an oxidizing agent, a persulfatecompound, an azole compound, a chelate compound, a surfactant andmixtures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating a surface of an internal circuitwhich was surface treated by a conventional brown oxide treatment methodthrough acid type etching;

FIG. 2 is a schematic view illustrating a surface of an internal circuitwhich was surface treated by a conventional basic reduction type blackoxide treatment method;

FIG. 3 is a schematic view illustrating a surface of an internal circuitwhich was surface treated by a conventional acidic dissolution typeblack oxide treatment method;

FIG. 4 is a cross-sectional view illustrating a structure of a PCBaccording to a first preferred embodiment of the present invention;

FIG. 5 is a cross-sectional view illustrating a structure of a PCBaccording to a second preferred embodiment of the present invention;

FIG. 6 is a schematic flow chart illustrating a process of manufacturinga PCB according to a preferred embodiment of the present invention;

FIGS. 7 to 11 are schematic flow diagrams illustrating a process ofmanufacturing a PCB according to the first preferred embodiment of thepresent invention; and

FIG. 12 is a schematic flow diagram illustrating a process ofmanufacturing a PCB according to the second preferred embodiment of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Various objects, advantages and features of the invention will becomeapparent from the following description of embodiments with reference tothe accompanying drawings.

The terms and words used in the present specification and claims shouldnot be interpreted as being limited to typical meanings or dictionarydefinitions, but should be interpreted as having meanings and conceptsrelevant to the technical scope of the present invention based on therule according to which an inventor can appropriately define the conceptof the term to describe most appropriately the best method he or sheknows for carrying out the invention.

The above and other objects, features and advantages of the presentinvention will be more clearly understood from the following detaileddescription taken in conjunction with the accompanying drawings. In thespecification, in adding reference numerals to components throughout thedrawings, it is to be noted that like reference numerals designate likecomponents even though components are shown in different drawings. Termsused in the specification, ‘first’, ‘second’, etc. can be used todescribe various components, but the components are not to be construedas being limited to the terms. The terms are only used to differentiateone component from other components.

Printed Circuit Board (PCB)

FIG. 4 is a cross-sectional view illustrating a structure of a PCBaccording to a first preferred embodiment of the present invention, andFIG. 5 is a cross-sectional view illustrating a structure of a PCBaccording to a second preferred embodiment of the present invention.

Referring to FIG. 4, the PCB according to the first preferred embodimentof the present invention comprises a base substrate 101 having a metalpattern for a circuit and a surface roughness formed on the metalpattern, wherein the surface roughness includes a first surfaceroughness 102 a in an anchor structure A and a second surface roughnesshaving a black oxide layer 104 in a needle structure B formed on thefirst surface roughness 102 a.

Since the first surface roughness 102 a has a macro-anchor structure,interlayer adhesion to a prepreg may be improved. Here, ‘macro’ meansthat the surface roughness is formed throughout the width and depth ofseveral micrometers (μm) in an etched region.

Then, by forming a second surface roughness having a black oxide layer104 in the secondarily formed micro-needle structure B on the firstsurface roughness 102 a, the interlayer adhesion to the prepreg may befurther increased.

Meanwhile, a thickness of the black oxide layer 104 may range from 0.05to 1.0 mg/cm², more preferably, 0.1 to 0.6 mg/cm². If this thickness isless than 0.05 mg/cm², the second surface roughness may beinsufficiently formed. On the other hand, if the thickness is more than1.0 mg/cm² and too large, roll marks may be generated on the PCB duringa horizontal roll process.

The second surface roughness may further include a reduction layer 105formed by treating a surface of the black oxide layer 104 using areducing agent containing a base during post-dipping.

The reduction layer 105 is substantially formed by reduction of a CuOlayer present on the surface of the black oxide layer structure into ametal Cu layer having favorable acid resistance, while possiblypreventing pink-rings from occurring when exposed to acid.

Referring to FIG. 5, the PCB according to the second preferredembodiment of the present invention comprises a base substrate 201having a metal pattern for a circuit and a surface roughness formed onthe metal pattern, wherein the surface roughness includes a firstsurface roughness 202 a in an anchor structure A and a second surfaceroughness having a black oxide layer 205 in a granular structure Cformed on the first surface roughness 202 a.

Since the first surface roughness 202 a has a macro-anchor structure,interlayer adhesion to a prepreg may be improved. Here, ‘macro’ meansthat the surface roughness is formed throughout the width and depth ofseveral micrometers (μm) in an etched region.

Then, by forming a second surface roughness having a black oxide layer205 in the secondarily formed granular structure C on the first surfaceroughness 202 a, the interlayer adhesion to the prepreg may be furtherincreased.

Here, the second surface roughness is a black oxide layer 205 in agranular structure C formed by treating a surface of the black oxidelayer, which has a micro-needle structure formed during black-oxidetreatment, using an acidic dissolving agent in the post-dipping process.

Meanwhile, a thickness of the black oxide layer 205 in a granularstructure C may range from 0.005 to 0.4 mg/cm², more preferably, 0.01 to0.3 mg/cm². If this thickness is more than the above range, the granularstructure of second surface roughness may be poorly formed due to thenon-uniform surface, otherwise, failure to prevent a pink-ring may occurdue to decreased acid resistance.

The black oxide layer 205 having a micro-granular structure C may beformed by, for example, dissolving CuO present on the surface of theblack oxide layer structure and converting the same into Cu₂O havingrelatively favorable acid resistance, thus efficiently preventing pinkrings from occurring when exposed to acid.

The foregoing drawings show the surface roughness in enlarged scale inorder to clearly illustrate a surface condition of the metal pattern,however, those skilled in the art will appreciate that such a scale doesnot correspond to an actual structural ratio of the surface roughness.

Although other detailed components of the PCB except for featured partsof the inventive preferred embodiment are omitted for clarity in theforegoing drawings, it will be apparent to those skilled in the art thata general PCB structure well-known in the art may be applied to theinventive preferred embodiment. In particular, each of the basesubstrates 101 and 201 may be any conventional multilayer circuit boardhaving at least one circuit layer on an insulating layer.

The multilayer circuit board may include not only a typical PCBconsisting of not more than 4 layers but also a multilayer PCB, a ballgrid array (BGA) PCB and other PCBs for special use.

In manufacturing a multilayer PCB, the inventive PCB exhibits acidresistance or corrosion resistance during an additional laminatingprocess, thus being preferably used as an internal substrate for themultilayer PCB, however, not being particularly limited thereto.Moreover, the inventive PCB may be used in various applicationsrequiring combination of a PCB with an adhesive resin or a metal layer.

The insulating layer may be prepared using a thermosetting resin such asepoxy resin, a thermoplastic resin such as polyimide, or any other resinthat contains not only any of the above resins but also a reinforcingagent such as glass fiber or inorganic filler impregnated therein, suchas a prepreg. Thermosetting resin and/or photo-curable resin may also beused. However, the resin used herein is not particularly limited tothose described above.

A metal used for the metal pattern for a circuit is not particularlylimited so long as it is a conductive metal used for manufacturing acircuit in PCB applications, and may typically include Cu or a Cu alloy.

As described above, the PCB of the present invention has a complexsurface roughness comprising a first surface roughness in a macro-anchorstructure and a second surface roughness in a micro-needle structure ora micro-granular structure. Therefore, when the inventive PCB is appliedto a PCB manufacturing process using a variety of prepregs that havenormal Tg, middle Tg, high Tg, low Dk, low Df and/or halogen-freeproperties, excellent interlayer adhesion may be attained. Especially,even when a BT resin having a relatively low impregnation rate due to ahigh Tg, as well as a low Dk, is used as the prepreg, excellentinterlayer adhesion may be obtained.

Moreover, since the inventive PCB has a complex surface roughness, athickness of a black oxide layer may be reduced, as compared to aconventional black-oxide treatment process. Accordingly, the presentinvention may solve a problem in that a black oxide layer in a needleform is crushed by a driven roll during a horizontal process which inturn generates roll marks, if the black oxide layer is thick.

Method for Manufacturing PCB

With regard to a method for manufacturing a PCB, the present inventorshave partially changed an oxide treatment method to improve interlayeradhesion by providing a roughness to a metal circuit during surfacetreatment of a metal surface for a circuit in a process of preparing aninternal layer, so as to form a surface roughness in a macro-structureduring etching, followed by forming another surface roughness in amicro-structure on the previous surface roughness having themacro-structure by a black-oxide treatment process. Optionally, apost-dipping process was further conducted using a basic reducing agentor an acidic dissolving agent, in order to produce a structure havingexcellent acid resistance. As a result, it was found that, when thisstructure having excellent acid resistance was applied to a process formanufacturing a PCB using a variety of prepregs having normal Tg, middleTg, high Tg, low Dk, low Df and/or halogen-free properties, interlayeradhesion is considerably improved. Especially, it was found that, if aBT resin having a low Dk and a low impregnation rate due to a high Tg isused as the prepreg, excellent adhesive properties such as highinterlayer adhesion may be attained. Based on the foregoing findings,the present invention had been completed.

With regard to the inventive method, formation of a surface roughness ina macro-structure means a process of forming a first surface roughnesswhile further formation of a surface roughness in a micro-structureafter the formation of the first surface roughness is referred to as aprocess of forming a second surface roughness.

A method for manufacturing a PCB according to the present inventionsubstantially includes: forming a first surface roughness by treating ametal surface for a circuit of the PCB using an etching solution toprovide an anchor structure, so as to form the first surface roughness;activating the first surface roughness by activating the metal surfacebefore black-oxide treatment thereof; and forming a second surfaceroughness by subjecting the activated metal surface into a black-oxidetreatment.

The formation of the surface roughness according to the presentinvention is substantially completed by the foregoing two-stage process,in particular, combining the macro-structure with the micro-structure toprepare a complex surface roughness. It was found that the resultedsurface roughness exhibits unexpected interlayer adhesion to variousinterlayer bonding resins, that is, prepregs having differentcharacteristics such as normal Tg, middle Tg, high Tg, low Dk, low Dfand/or halogen-free properties, as compared to the surface roughnessformed in separate stages. Specifically, even when a BT resin having alow Dk and a low impregnation rate due to a high Tg is used as theprepreg, favorable effects such as excellent interlayer adhesion may beobtained.

Furthermore, since the surface roughness is a complex surface roughnessformed in two-stages, a thickness of a black oxide layer prepared duringa black-oxide treatment process, which is the process of forming thesecond surface roughness, may be relatively reduced, as compared to aconventional black-oxide treatment process. Therefore, a problem in thata needle type black oxide layer is crushed by a driven roll during ahorizontal process which in turn generates roll marks, if the blackoxide layer is thick, may be successfully overcome.

The following description will be given to concretely explain preferredembodiments of the present invention, with reference to the accompanyingdrawings.

FIG. 6 is a schematic flow chart illustrating a process of manufacturinga PCB according to a preferred embodiment of the present invention;FIGS. 7 through 11 are schematic flow diagrams illustrating a process ofmanufacturing a PCB according to the first preferred embodiment of thepresent invention; and FIG. 12 is a schematic flow diagram illustratinga process of manufacturing a PCB according to the second preferredembodiment of the present invention.

Referring to FIG. 6, the method for manufacturing the PCB as describedabove comprises: degreasing a metal surface for a circuit of the PCB inoperation S101; treating the degreased metal surface for a circuit usingan etching solution to provide an anchor structure on the metal surface,thus forming a first surface roughness in operation S102; activating themetal surface before black-oxide treatment thereof, to activate thefirst surface roughness in operation S103; subjecting the metal surfaceinto a black-oxide treatment to form a second surface roughness inoperation S104; and post-dipping the black-oxide treated metal surfaceusing a basic reducing agent or an acidic dissolving agent, after theformation of the second surface roughness, in operation S105.

Hereinafter, referring to FIGS. 7 through 11, the first preferredembodiment of the present invention will be described in detail.

First, in FIG. 7, a surface of a circuit metal 102 in a PCB 100 whichcomprises a base substrate 101 having the circuit metal 102 is subjectedto degreasing in order to remove oxide and impurities from the surface.The degreasing of the metal surface for a circuit may be conducted usingan acidic or a basic type degreasing solution.

The acidic degreasing solution may contain an inorganic acid, an organicacid, alcohols, a surfactant, or the like.

The inorganic acid may be selected from a group consisting of generalinorganic acids such as sulfuric acid, nitric acid, phosphoric acid,hydrochloric acid, fluoric acid, boric acid, carboxylic acid, and thelike, and mixtures thereof.

The organic acid may be selected from a group consisting of generalorganic acids such as glyceric acid, glutaric acid, citric acid,salicyclic acid, adipic acid, ascorbic acid, oxalic acid, maleic acid,malic acid, malonic acid, succinic acid, benzoic acid, glycolic acid,heptanoic acid, tartaric acid, lactic acid, formic acid, propionic acid,acrylic acid, acetic acid, butyric acid, valeric acid, 2-methylbutyricacid, n-hexanoic acid, 3,3-dimethyl butyric acid, 2-ethyl butyric acid,4-methyl pentanoic acid, n-heptanoic acid, 2-methyl hexanoic acid,n-octanoic acid, 2-ethyl hexanoic acid, pimellic acid, phthalic acid,and the like, and mixtures thereof.

The alcohols may be selected from a group consisting of general alcoholssuch as ethanol, methanol, isobutyl alcohol, benzyl alcohol, isopropylalcohol, butanol, pentanol, hexanol, heptanol, octanol, isobutylalcohol, propanol, diacetone alcohol, isopropyl alcohol, polyvinylalcohol, propyl alcohol, perfuryl alcohol, diol, 3-chloro-1,2-propanediol, triol, 3-chloro-1-propanediol, 1-chloro-2-propanol,2-chloro-1-propanol, 3-chloro-1-propanol, 3-bromo-1,2-propanediol,1-bromo-2-propanol, 3-bromo-1-propanol, 3-iodo-1-propanol,4-chloro-1-butane, n-butanol, n-pentanol, n-hexanol, 2-chloroethanol,and the like, and mixture thereof.

The surfactant may be selected from a group consisting of cationic,amphoteric, anionic and non-ionic surfactants or mixtures thereof.

The basic degreasing solution may include an amine compound, basicsalts, a surfactant, and the like.

The amine compound may be selected from a group consisting of aminessuch as diethanolamine, triethylamine, triethanolamine, ethylamine,methylamine, hexylamine, isobutylamine, tert-butylamine, tributylamine,dipropylamine, dimethylamine, monoethanolamine, methyl diethanolamine,and the like, and mixtures thereof.

The basic salts may be selected from a group consisting of general basicsalts such as sodium hydroxide, potassium hydroxide, sodium silicate,sodium carbonate, and the like, or mixtures thereof.

The surfactant may be selected from cationic, amphoteric and non-ionicsurfactants, or mixtures thereof.

In the foregoing drawings, although other detailed components of the PCBexcept for featured parts of the inventive preferred embodiment areomitted for clarity, it will be apparent to those skilled in the artthat a general PCB structure well known in the art may be applied to theinventive method according to the foregoing preferred embodiments. Inparticular, the base substrate 101 may be any conventional multilayercircuit board having at least one circuit layer on an insulating layer.

A multilayer circuit board applicable to the inventive methods mayinclude not only a typical PCB consisting of not more than 4 layers butalso a multilayer PCB, a ball grid array (BGA) PCB and other PCBs forspecial use.

In manufacturing a multilayer PCB, the inventive PCB exhibits acidresistance or corrosion resistance during an additional laminatingprocess, thus being preferably used in manufacturing the multilayer PCB,however, not being particularly limited thereto. Moreover, the inventivePCB may be used in various applications requiring combination of a PCBwith an adhesive resin or a metal layer.

The insulating layer may be prepared using a thermosetting resin such asepoxy resin, a thermoplastic resin such as polyimide, or any other resinthat contains any of the above resins and a reinforcing agent such asglass fiber or inorganic filler impregnated therein, such as a prepreg.Thermosetting resin and/or photo-curable resin may also be used.However, the resin used herein is not particularly limited to thosedescribed above.

The circuit metal 102 is not particularly limited so long as it is aconductive metal used for manufacturing a circuit in PCB applications,and may typically include Cu or a Cu alloy.

Next, referring to FIG. 8, after degreasing a surface of the circuitmetal 102, the degreased surface is subjected to treatment using anetching solution to provide an anchor structure, so as to form a firstsurface roughness 102 a having a macro-anchor structure A on the surfaceof the circuit metal 102.

The etching solution for forming an anchor structure on a surface of thecircuit metal may be a general etchant alone, an etching solutioncomprising two or more of the general etchant and a specific etchant forforming an anchor structure as a mixture form, a solution of the etchantfor forming an anchor structure in deionized water, and/or the etchantfor forming an anchor structure alone.

The foregoing etchant may include, for example, a ferrite chlorideetchant, a cupric chloride etchant, an alkaline etchant, a hydrogenperoxide and sulfuric acid etchant, a formic acid and cupric chlorideetchant, an acetic acid and cupric chloride etchant, a sodium persulfateetchant, a potassium persulfate etchant, an ammonium persulfate etchant,a potassium monosulfate peroxide etchant, a perchlorite etchant, apermanganic acid etchant, a peroxide etchant, a dichromate etchant, andthe like.

The etchant for forming an anchor structure may contain an inorganicacid, an organic acid, an oxidizing agent, azole compounds, and thelike.

The inorganic acid may be selected from a group consisting of generalinorganic acids such as sulfuric acid, nitric acid, phosphoric acid,hydrochloric acid, fluoric acid, boric acid, carboxylic acid, and thelike, and mixtures thereof.

The organic acid may be selected from a group consisting of generalorganic acids such as glyceric acid, glutaric acid, citric acid,salicyclic acid, adipic acid, ascorbic acid, oxalic acid, maleic acid,malic acid, malonic acid, succinic acid, benzoic acid, glycolic acid,heptanoic acid, tartaric acid, lactic acid, formic acid, propionic acid,acrylic acid, acetic acid, butyric acid, valeric acid, 2-methylbutyricacid, n-hexanoic acid, 3,3-dimethyl butyric acid, 2-ethyl butyric acid,4-methyl pentanoic acid, n-heptanoic acid, 2-methyl hexanoic acid,n-octanoic acid, 2-ethyl hexanoic acid, pimellic acid, phthalic acid,and the like, and mixtures thereof.

The oxidizing agent may be selected from a group consisting of generaloxidizing agents such as hydrogen peroxide, urea hydrogen peroxide,percarbonate, benzoyl peroxide, peracetic acid, di-t-butyl peroxide,persulfate, sodium peroxide, periodic acid, periodate, perboric acid,perborate, permanganic acid, permanganate, iodic acid, iodate, ceriumammonium nitrate, ferric nitrate, and the like, or mixtures thereof.

The azole compound may include, for example, imidazole, thiazole,triazole or tetrazole compounds, which are used alone or in combinationof two or more thereof.

The imidazole compound may be selected from a group consisting ofimidazole, 2-ethylimidazole, 2-methylimidazole,2-ethyl-4-methylimidazole, 2-phenylimidazole, benzoimidazole,2-ethylbenzoimidazole, 2-methylbenzoimidazole, 5-methylbenzoimidazole,2-phenylbenzoimidazole, 2-mercaptobenzoimidazole, 2-isopropylimidazole,2-propylimidazole, 2-butylimidazole, 4-methylimidazole,2,4-dimethylimidazole, 2-aminoimidazole, mercatobenzoimidazole,2-bromobenzyl benziimidazole, 2-chlorobenzyl benziimidazole,2-bromophenyl benziimidazole, 2-chlorophenyl benziimidazole,2-bromoethylphenyl benziimidazole, 2-chloroethylphenyl benziimadazole,2-undecyl-4-methylimidazole, and the like.

The thiazole compound may be selected from a group consisting ofthiazole, 2-ethylthiazole, 2,4-dimethylthiazole, 4,5-dimethylthiazole,2-aminothiazole, 2-amino-2-thiazoline, 2-aminomethylthiazole,2-amino-4-methylthiazole, 1,2-thiazole, 1,3-thiazole, benzothiazole,1,2-benzothaizole, 1,3-benzothiazole, 2-aminobenzothiazole,2-mercaptobenzothiazole, 2-isopropyl-4-methylthiazole,5-formyl-4-methylthiazole, 5-amino-3H-thiazole, and the like.

The triazole compound may be selected from a group consisting of1,2,3-triazole, 1,2,4-triazole, 3-amino-1,2,4-triazole,5-phenyl-1,2,4-triazole, 5-amino-1,2,4-triazole, benzotriazole, sodiumbenzotriazole, 1-methyl-benzotriazole, tollytriazole, sodiumtollytriazole, 4-amino-1,2,4-triazole, 3-amino-5-methyltriazole,3-amino-5-ethyltriazole, 3,5-diamino-1,2,4-triazole,3-amino-1,2,4-triazole-5-carboxylic acid, 5-amino-1,2,3,4-thiatriazole,and the like.

The tetrazole compound may be selected from a group consisting of1H-tetrazole, 5-amino-1H-tetrazole, 5-methyl-H-tetrazole,5-phenyl-1H-tetrazole, 5-mercapto-1H-tetrazole,1-phenyl-5-mercapto-1H-tetrazole, 1-methyl-5-aminotetrazole,1-ethyl-5-aminotetrazole, α-benzyl-5-aminotetrazole,β-benyl-5-aminotetrazole, 1-(β-aminoethyl)tetrazole, and the like.

Using the etching solution, a first surface roughness 102 a in amacro-structure may be formed.

However, the foregoing examples are only described for illustrativepurposes and not particularly limited thereto so long as they can forman anchor structure.

The first surface roughness 102 a has an anchor structure, thusproviding improved interlayer adhesion when adhering to a prepreg.

For formation of the first surface roughness 102 a in a macro-structure,the term ‘macro’ means that the surface roughness is formed throughoutthe width and depth of several micrometers in an etched region.

A content of the etchant for forming an anchor structure among theetching solution may range from 0.5 to 30 wt. %, more preferably, 1 to15 wt. %. If the content is less than 0.5 wt. %, the metal surface maybe insufficiently etched. If the content exceeds 30 wt. %, the metalsurface may be over-etched, thus causing difficulties in the formationof surface roughness. Therefore, a first surface roughness is preferablyformed by controlling the content within the foregoing range.

Next, using a pre-dipping solution containing an active ingredientconsisting of an organic acid, an inorganic acid, a base and/or anoxidizing agent alone or in combination of two or more thereof, apre-dipping process may be conducted to activate a surface of the metalcircuit before black-oxide treatment.

The inorganic acid used herein may be selected from a group consistingof general inorganic acids such as sulfuric acid, nitric acid,phosphoric acid, fluoric acid, boric acid, carboxylic acid, and thelike, or mixtures thereof.

The organic acid used herein may be selected from a group consisting ofgeneral organic acids such as glyceric acid, glutaric acid, citric acid,salicyclic acid, adipic acid, ascorbic acid, oxalic acid, maleic acid,malic acid, malonic acid, succinic acid, benzoic acid, glycolic acid,heptanoic acid, tartaric acid, lactic acid, formic acid, propionic acid,acrylic acid, acetic acid, butyric acid, valeric acid, 2-methylbutyricacid, n-hexanoic acid, 3,3-dimethyl butyric acid, 2-ethyl butyric acid,4-methyl pentanoic acid, n-heptanoic acid, 2-methyl hexanoic acid,n-octanoic acid, 2-ethyl hexanoic acid, pimellic acid, phthalic acid,and the like, or mixtures thereof.

The base used herein may include hydroxide compounds, for example, beselected from a group consisting of general bases such as sodiumhydroxide, potassium hydroxide, barium hydroxide, ammonium hydroxide,tetramethylammonium hydroxide, tetraethylammonium hydroxide, and thelike, or mixtures thereof.

The oxidizing agent used herein may be selected from a group consistingof general oxidizing agents such as NaClO, NaClO₂, NaClO₃, KClO, KClO₂,KClO₃, hydrogen peroxide, urea hydrogen peroxide, and the like, ormixtures thereof.

A content of the active ingredient among the pre-dipping solution mayrange from 1 to 50 wt. %, more preferably, 5 to 30 wt. %. If the contentis less than 1 wt. %, a surface of the circuit metal may not beactivated, thus not preventing smooth black-oxide treatment. If thecontent is more than 50 wt. % and too large, a black-oxide treatedstructure may be rapidly formed during an additional process, that is,black-oxide treatment, thus decreasing a strength of the structure.Otherwise, the metal surface may be over-etched and cause defectsthereon.

Thereafter, referring to FIG. 9, the metal surface activated bypre-dipping is subjected to black-oxide treatment, so as to form asecond surface roughness having a black oxide layer 104 in a needlestructure B on the first surface roughness 102 a having the anchorstructure A.

The black-oxide treatment is preferably performed using a black-oxidetreating reaction solution which contains a mixture of an oxidizingagent and a base at 60 to 90° C. for 0.5 to 30 minutes.

The oxidizing agent used herein may be selected from a group consistingof general oxidizing agents such as NaClO, NaClO₂, NaClO₃, KClO, KClO₂,KClO₃, and the like, or mixtures thereof.

The base used herein may include hydroxide compounds, for example, beselected from a group consisting of general bases such as sodiumhydroxide, potassium hydroxide, barium hydroxide, ammonium hydroxide,tetramethylammonium hydroxide, tetraethylammonium hydroxide, and thelike, or mixtures thereof.

A content of the oxidizing agent may range from 1 to 80 wt. %, morepreferably, 5 to 60 wt. % relative to a total weight of the black-oxidetreating reaction solution. If this content is less than 1 wt. %, ablack oxide layer may be insufficiently formed. When the content is morethan 80 wt. % and too large, a black-oxide treated structure may berapidly formed, thus decreasing the strength of the structure.

A content of the base may range from 1 to 60 wt. %, more preferably, 5to 45 wt. % relative to a total weight of the black-oxide treatingreaction solution. If this content is less than 1 wt. %, a black oxidelayer may be insufficiently formed. When the content is more than 60 wt.% and is too large, a surface of the PCB may be tinged with red due toan increase in a red Cu₂O layer rather than a black CuO layer. If thislayer is not completely removed in an additional washing process due tostrong alkaline chemicals, problems may be caused during post-dipping.In addition, since a black-oxide treated structure is rapidly formed,the structure may have decreased strength.

A thickness of the black oxide layer formed during black-oxide treatmentaccording to the present invention may be controlled depending upon aconcentration of an oxidizing agent and a base, a temperature and areaction time. The thickness may range from 0.05 to 1.0 mg/cm², morepreferably, 0.1 to 0.6 mg/cm². If the thickness is less than 0.05mg/cm², the second surface roughness may be insufficiently formed. Whenthe thickness is more than 1.0 mg/cm² and too large, roll marks may begenerated on the PCB during a horizontal roll process. Therefore, thethickness of the black oxide layer is preferably controlled within theforegoing range, so as to improve interlayer adhesion to a prepreg andprevent roll marks during the horizontal roll process.

Next, referring to FIG. 10, the black-oxide treated metal surface issubjected to post-dipping to treat the surface using a basic reducingagent containing a base, thereby forming a reduced metal layer 105.

The reduction treatment is a process of converting (reducing) a metallayer provided on a surface of the black-oxide treated structure, forexample, a CuO layer into a Cu metal layer having excellent acidresistance. Therefore, similar to a process for manufacturing amultilayer PCB, the reduction process may be conducted if acidresistance is required during an additional process, in order to preventpink-rings from occurring when exposed to acid.

The basic reducing agent may be selected from a group consisting ofdimethylamine borane (DMAB), morpholine borane (MPB), formalin (HCHO),sodium borohydride (NaBH₄), potassium borohydride (KBH₄) and mixturesthereof, however, is not particularly limited thereto.

The base may be selected from a group consisting of general bases suchas sodium hydroxide, potassium hydroxide, barium hydroxide, ammoniumhydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide,and the like, or mixtures thereof.

The following description will be given to explain a method according toa second preferred embodiment of the present invention with reference toFIG. 12.

With regard to the method of the second preferred embodiment, respectiveprocesses for degreasing, formation of a first surface roughness,activation of the first surface roughness and formation of a secondsurface roughness are substantially the same as described in FIGS. 7through 9, therefore, a detailed description thereof will be omitted forclarity. Instead, a post-dipping process according to the secondpreferred embodiment of the present invention will be described below,with reference to FIG. 12.

Referring to FIG. 12, the black-oxide treated metal surface as shown inFIG. 9 is subjected to post-dipping to treat the metal surface using anacidic dissolving agent, thereby forming a black oxide layer 205 in agranular structure C.

The black oxide layer 205 in a granular structure C may have a thicknessin the range of 0.005 to 0.4 mg/cm², more preferably, 0.01 to 0.3mg/cm². If this thickness is beyond the above range, a surface roughnessin a granular structure may be poorly formed due to non-uniform surface,otherwise, failure in preventing pink-rings occurring due to decreasedacid resistance.

The black oxide layer 205 having a micro-granular structure C may beformed by dissolving a metal layer, for example, a CuO layer present onthe surface of the black oxide layer structure and converting the sameinto a Cu₂O layer having relatively favorable acid resistance, thusefficiently preventing pink rings from occurring when exposed to acid.

As shown in FIG. 11, a second surface roughness having a black oxidelayer 104 in a needle structure B is formed on the first surfaceroughness 102 a during the black-oxide treatment process, and, as shownin FIG. 12, the needle structure B is converted into a granularstructure C by treating the second surface roughness using an acidicdissolving agent during the post-dipping process, thus resulting in theblack oxide layer 205 in the granular structure C and improvinginterlayer adhesion to a prepreg.

The acidic dissolving agent may contain an inorganic acid, an organicacid, an oxidizing agent, a persulfate compound, an azole compound, achelate compound, a surfactant, and the like, alone or in combinationthereof.

The inorganic acid may be selected from a group consisting of generalinorganic acids such as sulfuric acid, nitric acid, phosphoric acid,hydrochloric acid, fluoric acid, boric acid, carboxylic acid, and thelike, and mixtures thereof.

The organic acid may be selected from a group consisting of generalorganic acids such as glyceric acid, glutaric acid, citric acid,salicyclic acid, adipic acid, ascorbic acid, oxalic acid, maleic acid,malic acid, malonic acid, succinic acid, benzoic acid, glycolic acid,heptanoic acid, tartaric acid, lactic acid, formic acid, propionic acid,acrylic acid, acetic acid, butyric acid, valeric acid, 2-methylbutyricacid, n-hexanoic acid, 3,3-dimethyl butyric acid, 2-ethyl butyric acid,4-methyl pentanoic acid, n-heptanoic acid, 2-methyl hexanoic acid,n-octanoic acid, 2-ethyl hexanoic acid, pimellic acid, phthalic acid,and the like, and mixtures thereof.

The oxidizing agent may be selected from a group consisting of generaloxidizing agents such as hydrogen peroxide, urea hydrogen peroxide,percarbonate, benzoyl peroxide, peracetic acid, di-t-butyl peroxide,persulfate, sodium peroxide, periodic acid, periodate, perboric acid,perborate, permanganic acid, permanganate, iodic acid, iodate, ceriumammonium nitrate, ferric nitrate, and the like, or mixtures thereof.

The persulfate compound may be selected from sodium persulfate,potassium persulfate, ammonium persulfate, potassium monosulfateperoxide, and the like.

The azole compound may include, for example, imidazole, thiazole,triazole and/or tetrazole compounds, which are used alone or incombination of two or more thereof.

The chelate compound may be selected from a group consisting of, forexample, iminodiacetate, acetylacetonate,1,2-cyclohexanediamine-N,N,N′N′-tetraacetic acid, triethylamine,triethanolamine, ethylamine, methylamine, isobutylamine,tert-butylamine, tributylamine, dipropylamine, dimethylamine,ethylenediamine tetraacetic acid, hydroxyethyl ethylenediamine triaceticacid diglycolamine, monoethanolamine, methyldiethanolamine, aniline,Rochelle salt, Quadrol, organic phosphate, aminocarboxylic acid,diethylenetriamine pentaacetic acid, nitriloacetic acid, phosphoricacid, ethylenediamine tetramethylene phosphoric acid, diethylenetriaminepentamethylene phosphoric acid, nitrilotrimethylene phosphoric acid,polycarboxylic acid, Blue cornate, citrate, polyacrylate, polyaspartate,and the like.

The surfactant may be selected from a group consisting of cationic,amphoteric, anionic and/or non-ionic surfactants, or mixtures thereof.

As described above, a method for manufacturing a PCB according to thepresent invention may be employed in a wide range of applicationsincluding, for example, high reliability products as well as generalproducts. Therefore, the inventive method is suitable for a wide rangeof processes for treatment of products. Moreover, the present inventionmay be employed in both a vertical process and a horizontal processgenerally used in the art.

As further shown in FIG. 11, it was found that the inventive methodattains improved interlayer adhesion to various interlayer bondingresins having different characteristics such as normal Tg, middle Tg,high Tg, low Dk, low Df and/or halogen-free properties. For instance,even when using a BT resin layer 106 with a low Dk and a lowimpregnation rate due to a high Tg, as a prepreg, excellent effects suchas high interlayer adhesion may be obtained.

In addition, since a complex surface roughness is formed in a two-stageprocess, a thickness of a black oxide layer formed during black-oxidetreatment which is a process of forming a second surface roughness, maybe decreased. Accordingly, the present invention may solve a problem inthat a black oxide layer in a needle form is crushed by a driven rollerduring a horizontal process which in turn generates roll marks, if theblack oxide layer is thick.

Hereinafter, the present invention will be described in detail bycomparing the inventive examples with a comparative example, however,the scope of the present invention is not particularly limited thereto.

Example 1

According to a process sequence illustrated in FIG. 6, surface treatmentof a circuit metal for a PCB was performed.

A degreasing process was conducted by treating a test specimen made of acopper clad laminate (CCL; 406 mm×510 mm, 0.1 mm in thickness) and acopper foil (330 mm×400 mm, 35 μm in thickness) using a solution of 20wt. % MC100 (KENSCO Co., a basic cleaner) in deionized water at 60° C.for 1 minute and then washing the same.

After the degreasing process, an etching process was conducted bytreating the test substrate, that is, the specimen (made of CCL and Cufoil) in an etching solution comprising 12 wt. % of sodium persulfate, 5wt. % of sulfuric acid and 15 wt. % of BF200A (KENSCO Co., a roughnessforming etchant) and the remainder of deionized water at roomtemperature for 1 minutes and then washing the same.

After the etching process, a pre-dipping process was conducted bytreating the etched specimen using a solution of 30 wt. % BF300A (KENSCOCo., a metal surface-activating agent) in deionized water at roomtemperature for 1 minute.

Next, a black-oxide treatment process was conducted by treating thepre-dipped specimen using a mixture comprising 55 wt. % of BF400A(KENSCO Co., an oxidizing agent) and 25 w.% of BF400B (KENSCO Co., abase) in deionized water at 80° C. for 1 minute, so as to form a blackoxide layer.

Thereafter, a post-dipping process was conducted by treating theblack-oxide treated specimen using a reducing solution comprising 20 wt.% of BF500A (KENSCO Co., a reducing agent) and 10 wt. % of BF500B(KENSCO Co., a base) in deionized water at 45° C. for 1 minute.

Example 2

The present experiment was substantially performed according to the sameprocedures as described in Example 1, except that the post-dippingsolution used herein was a dissolving solution comprising 40 wt. % ofHR400A (KENSCO Co., a dissolving agent) and 10 wt. % of HR400B (KENSCOCo., a dissolving agent) in deionized water and the post-dipping processwas conducted at 45° C. for 1 minute.

The black oxide layer of the specimen prepared according to theforegoing example had an average film thickness of 0.1 to 0.6 mg/cm².

Comparative Example 1

The present experiment was substantially performed according to the sameprocedures as described in Example 1, except that the etching processduring black-oxide treatment was conducted using an etching solutioncomprising 12 wt. % sodium persulfate, 5 wt. % of sulfuric acid and theremainder of deionized water at room temperature for 1 minute, followedby washing, and the black-oxide treatment was conducted using a mixturecomprising 55 wt. % of BF400A (KENSCO Co., an oxidizing agent), 25 wt. %of BF400B (KENSCO Co., a base) and the remainder of deionized water at85° C. for 3 minutes, so as to form a black oxide layer.

Experimental Example

For assessment of reliability, a CCL specimen (406 mm×510 mm) with apredetermined thickness was firstly prepared, and weighed before andafter formation of a black oxide layer thereon. Then, a difference inmeasured weights of the specimen was calculated to estimate a thicknessof the black oxide layer. Alternatively, for determination of an etchingrate, the CCL specimen (100 mm×100 mm) was cut into pieces having apredetermined size and each cut piece was weighed before and after theetching process. Then, a difference in measured weights of the specimenwas calculated to determine the etching rate. For the inventive example,the thickness of the black oxide layer was constantly maintained in therange from 0.8 to 1.2 μm. Furthermore, interlayer adhesion between theCu foil and resin was assessed by the following procedures. According toassessment items and procedures listed in Table 1, a prepreg (BT resin,GHPL-830, Tg=215° C.) and the treated Cu foil specimen (300 mm×400 mm,35 μm in thickness) were stacked in this order above a bottom plate,followed by making the laminated specimen to a predetermined size(width: 10 mm) then etching the Cu foil. The remainder Cu foil wassubjected to measurement of the peel strength using a tensile strengthcompressor. Measurement of roll marks was performed by processing aproduct in a horizontal black-oxide treatment line of the manufacturerafter the foregoing treatments of the product.

TABLE 1 Assessment Item Assessment standard Note Cu interlayer adhesionMore than 0.4 kgf/cm Standard: (peel strength) Cu foil 35 μm Accordingto prepreg cycle Manufacturing: According to press cycle Analysis ofroll marks Standard: 0.1 T,12/12 material

Test results regarding interlayer adhesion, roll marks, and the like, asdescribed in Examples 1 and 2 and Comparative Example, are shown inTABLE 2.

TABLE 2 Interface adhesion Section to BT resin (kgf/cm) Roll markExample 1 0.75 Extremely less (excellent) Example 2 0.68 Less (good)Comparative 0.15 Numerous Example 1 (fault, insufficient)

From Table 2, it can be seen that Examples 1 and 2 achieved peelstrengths of 0.75 and 0.69 kgf/cm, respectively, which are remarkablyimproved, as compared to Comparative Example 1. The reason for thisexcellent result is considered due to that a macro-anchor structure isimpregnated with the BT resin, followed by permeation of the BT resininto a micro-needle structure of the black oxide layer, therebyincreasing the interlayer adhesion between the Cu surface and the BTresin.

It was also found that roll marks are reduced in Examples 1 and 2,compared to Comparative Example 1. The reason for this result isconsidered due to that the present invention provides a complex surfaceroughness capable of decreasing a thickness of a black oxide layer, ascompared to a conventional black-oxide treatment process, therebyreducing squashing (that is, dents) by a driven roller.

Consequently, a surface treatment method according to the presentinvention includes a process for formation of a first surface roughnessthat treats a surface of a metal circuit in a PCB with an etchingsolution for forming an anchor structure to form a surface roughness,and a process for activation of the surface of the metal circuit beforeblack-oxide treatment thereof after formation of the first surfaceroughness. As a result, the anchor structure, that is, an alternativemacro-surface roughness may be obtained, as compared to existing surfacetreatment of a Cu surface. Thereafter, this macro-surface roughness issubjected to a black-oxide treatment process, so as to form a secondsurface roughness in a needle structure. Because of this complex surfaceroughness, adhesive properties to a variety of interlayer bonding resins(that is, a prepreg) having specific characteristics such as high Tg,low Dk, low Df and/or halogen-free properties may be noticeablyenhanced.

In addition, because of the complex surface roughness, a thickness ofthe black oxide layer may be relatively decreased, as compared to aconventional black-oxide treatment process. In particular, the presentinvention may control the thickness of the black oxide layer to a lowlevel in the range of 0.1 to 0.6 mg/cm², thus sufficiently decreasingroll marks generated in a horizontal roll line. Moreover, a black-oxidetreatment time may be reduced by 15 to 20 seconds than a conventionalmethod, thereby enhancing production efficiency.

As described above, the present invention is preferably applicable tomanufacturing of higher density, higher integration, ultra-thinner andhigh value-added products, which have recently been attracting attentionin response to rapidly advancing trends in electronic technologies, andmay provide a method for manufacturing a multilayer PCB satisfying theforegoing demands.

When the present invention is employed in manufacturing a productfabricated using a specific resin with high Tg, low Dk, low Df and/orhalogen-free properties as a prepreg, improved adhesive propertiesunexpected by conventional arts may be achieved.

Moreover, the inventive method may solve a problem such as occurrence ofnumerous roll marks by a horizontal roll process during a conventionalblack-oxide treatment process, thereby producing improved PCBs suitablefor application in a horizontal line. Furthermore, since an alternativeapparatus is not required, the present invention may also have economicadvantages.

Additionally, the inventive method may be employed in both a verticalline and a horizontal line generally used in the art, and may be widelyused for manufacturing high reliability products as well as generalproducts.

Although the preferred embodiments of the present invention have beendisclosed for illustrative purposes, the printed circuit board (PCB) andthe method for manufacturing the same according to the present inventionare not limited thereto. Those skilled in the art will appreciate thatvarious modifications, additions and substitutions are possible, withoutdeparting from the scope and spirit of the invention.

Accordingly, simple modifications and changes of the present inventionshould also be understood to fall within the present invention, thescope of which is defined in the appended claims and their equivalents.

What is claimed is:
 1. A printed circuit board (PCB), comprising: a basesubstrate having a metal pattern for a circuit; and a surface roughnessprovided on the metal pattern, wherein the surface roughness has a firstsurface roughness in an anchor structure and a second surface roughnesshaving a black oxide layer in a granular structure formed on the firstsurface roughness.
 2. The PCB as set forth in claim 1, wherein the blackoxide layer has a thickness of 0.005 to 0.4 mg/cm².
 3. The PCB as setforth in claim 1, wherein a metal of the metal pattern for a circuitcomprises Cu or a Cu alloy.